Book Image

Linux Kernel Debugging

By : Kaiwan N. Billimoria
Book Image

Linux Kernel Debugging

By: Kaiwan N. Billimoria

Overview of this book

The Linux kernel is at the very core of arguably the world’s best production-quality OS. Debugging it, though, can be a complex endeavor. Linux Kernel Debugging is a comprehensive guide to learning all about advanced kernel debugging. This book covers many areas in-depth, such as instrumentation-based debugging techniques (printk and the dynamic debug framework), and shows you how to use Kprobes. Memory-related bugs tend to be a nightmare – two chapters are packed with tools and techniques devoted to debugging them. When the kernel gifts you an Oops, how exactly do you interpret it to be able to debug the underlying issue? We’ve got you covered. Concurrency tends to be an inherently complex topic, so a chapter on lock debugging will help you to learn precisely what data races are, including using KCSAN to detect them. Some thorny issues, both debug- and performance-wise, require detailed kernel-level tracing; you’ll learn to wield the impressive power of Ftrace and its frontends. You’ll also discover how to handle kernel lockups, hangs, and the dreaded kernel panic, as well as leverage the venerable GDB tool within the kernel (KGDB), along with much more. By the end of this book, you will have at your disposal a wide range of powerful kernel debugging tools and techniques, along with a keen sense of when to use which.
Table of Contents (17 chapters)
1
Part 1: A General Introduction and Approaches to Kernel Debugging
4
Part 2: Kernel and Driver Debugging Tools and Techniques
11
Part 3: Additional Kernel Debugging Tools and Techniques

Building your kernel and modules with Clang

Low Level Virtual Machine (LLVM) is the original name given to this modular compiler tooling project. It now doesn't have much to do with traditional virtual machines and is instead a powerful backend for several compilers and toolchains.

Clang (the pronunciation rhymes with "slang") is a modern compiler frontend technology for C-type languages (includes support for C, C++, CUDA, Objective C/C++, and more) and is based on the LLVM compiler. It's considered a drop-in replacement for GCC. Clang currently seems to have a significant advantage over GCC – especially from our point of view – generating superior diagnostics as well as being able to intelligently generate code avoiding OOB accesses. This is critical. It paves the way to superior code. We saw (in the previous section on KASAN) that faulty left-OOB accesses on global memory, not reliably caught by GCC (versions 9.3, 10, and 11), are caught with...